The present invention relates to a water repellent composition for a substrate to be exposed, a method for forming a resist pattern, an electronic device produced by the formation method, a treatment method for imparting water repellency to a substrate to be exposed, a water repellent set for a substrate to be exposed, and a treatment method for imparting water repellency to a substrate to be exposed using the same.
In recent years, among production processes of electronic devices (for example, semiconductor devices, liquid crystal display elements, magnetic heads, and microlenses), particularly in the production process of semiconductor devices, development of an immersion lithography process used for the production of the semiconductor device has been actively performed, the process includes performing exposure through the space between a projection optical system of an exposure device, and the substrate (including a semiconductor substrate and a wafer) to be exposed filled with an immersion liquid. As the immersion liquid, pure water is commonly used. However, in this process, there is a problem that the immersion liquid to be used in this exposure treatment flows into a back side through a periphery portion of the surface to be treated of the substrate to be exposed to contaminate the backside of the substrate to be exposed.
As a method for enhancing the water repellency of a wafer, a surface treatment using hexamethyldisilazane (HMDS) has been widely employed. However, the treatment by HMDS is not premised on the immersion lithography method and its water repellency is insufficient. For this situation, a method of using a silylation agent having a fluorine-substituted alkyl group or alkenyl group (Patent Document 1: JP-A No. 2007-019465), a method in which the treatment by HMDS is coated to a region within a specific area on a backside of a semiconductor substrate (Patent Document 2: JP-A No. 2007-194503) and the like are proposed.
However, in the method of Patent Document 1, there is a problem that a chemical solution, such as a resist, coated to the surface of a substrate is repelled by the surface and some locations where the chemical solution is not coated are generated, and in the method of Patent Document 2, there is a problem that water repellency is insufficient. Further, while an organic film such as a resist film is formed on a substrate on which a film to be processed has been formed for forming a resist pattern, the methods of Patent Documents 1 and 2 have a problem that an adhesive force between the film to be processed and the organic film directly overlying that film is insufficient, leading to peeling of the film from a wafer edge, and a foreign substance by film peeling is mixed with an immersion liquid due to the convection of the immersion liquid during immersion lithography to induce pattern defects. Furthermore, if the adhesive force between the film to be processed and the organic film directly overlying that film is insufficient, there is a problem that destruction of the resist pattern easily takes place. The destruction of the resist pattern means that an aspect ratio (that is, film thickness H/line width d) of the resist pattern increases as the resist pattern is microfabricated, an area of the contact of a substrate with the resist pattern becomes small, and therefore the resist patter is easily destructed.